U.S. patent number 4,310,182 [Application Number 06/048,726] was granted by the patent office on 1982-01-12 for internal couplings for plastic solar collectors and the like.
This patent grant is currently assigned to Sealed Air Corporation. Invention is credited to Benjamin E. Vandenbossche.
United States Patent |
4,310,182 |
Vandenbossche |
January 12, 1982 |
Internal couplings for plastic solar collectors and the like
Abstract
A self-tapping coupling for plastic piping has a hollow
cylindrical section with external self-tapping threads and a
sealing member with an O-ring whereby the sealing member is
retained in the end of the plastic pipe by the threads cut by the
cylindrical section when the latter is inserted in the end of the
pipe with rotation.
Inventors: |
Vandenbossche; Benjamin E.
(Hillsborough, CA) |
Assignee: |
Sealed Air Corporation (Saddle
Brook, NJ)
|
Family
ID: |
21956125 |
Appl.
No.: |
06/048,726 |
Filed: |
June 15, 1979 |
Current U.S.
Class: |
285/40; 126/663;
165/76; 285/239; 285/423; 138/89; 165/178; 285/353 |
Current CPC
Class: |
F16L
47/20 (20130101); F24S 80/30 (20180501); F16L
55/1108 (20130101); B29C 65/4895 (20130101); Y02E
10/40 (20130101) |
Current International
Class: |
F16L
55/10 (20060101); F16L 47/00 (20060101); F16L
47/20 (20060101); F16L 55/11 (20060101); F24J
2/46 (20060101); F24J 2/00 (20060101); B29C
65/48 (20060101); F16L 035/00 (); B65D 051/00 ();
F16L 041/04 (); F16L 055/00 () |
Field of
Search: |
;138/89
;285/40,239,238,353,423,DIG.19,255 ;167/76,178 ;126/448,447 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
446021 |
|
Jan 1948 |
|
CA |
|
2354554 |
|
May 1974 |
|
DE |
|
Primary Examiner: Stephan; Steven L.
Attorney, Agent or Firm: Lerner, David, Littenberg &
Samuel
Claims
I claim:
1. In combination, a plastic manifold for a solar collector panel,
said manifold including an open end and a counterbore formed in
said open end to provide an internal shoulder within said manifold;
and an internal fitting removeably received in said counterbore of
said manifold for controlling fluid flow therethrough, said
internal fitting including a first member positioned in said
counterbore of said manifold for axial movement relative thereto,
said first member having a first external surface located
interiorally of said manifold and first permitting means for
permitting fluid to pass through said first member, a second member
fixedly positioned in said counterbore of said manifold, said
second member having a second external surface positioned between
said first external surface of said first member and said open end
of said manifold and second permitting means for permitting fluid
to pass through said second member, said second permitting means
being in fluid communication with said first permitting means so
that fluid can flow through said fitting and hence through said
open end of said manifold, sealing means provided on said first
external surface of said first member for forming a fluid-tight
seal between said first external surface of said first member and
an internal surface of the counterbored portion of said manifold,
connecting means provided on said first member for connecting said
fitting to a conduit, said connecting means passing through said
second member, and thread-cutting means provided on said second
external surface of said second member for cutting internal threads
in said manifold, said thread-cutting means cooperating with the
internal threads cut by said thread-cutting means to fixedly
position said second member in said counterbore of said manifold,
whereby said second member prevents the inadvertent removal of said
first member from said open end of said manifold.
2. A combination according to claim 1, wherein said connecting
means passes through said first permitting means and extends
exteriorally of said manifold.
3. A combination according to claim 2, wherein said second member
is made from a plastic selected from a group consisting of ABS and
PVC plastics.
4. A combination according to claim 3, wherein said sealing means
is an O-ring.
5. A combination according to claim 4, wherein said thread-cutting
means is a plurality of self-tapping threads.
6. A method of coupling a plastic manifold of a solar collector
panel to a plastic conduit such that fluid may flow between the
conduit and an open end of the manifold, comprising the steps of
counterboring the open end of the manifold to form a counterbore
therein; providing an internal fitting which includes a first
member, said first member being manufactured from plastic and
including sealing means for forming a fluid-tight seal, connecting
means for connecting said first member to the conduit and first
permitting means for permitting fluid to pass through said first
member, and a second member, said second member including
thread-cutting means for cutting internal threads and second
permitting means for permitting fluid to pass through said second
member; inserting said first member of said fitting into the
counterbore of the manifold such that said sealing means forms a
fluid-tight seal between an external surface of the sealing means
and an internal surface of the manifold; inserting said second
member of said fitting into the counterbore of the manifold such
that said second permitting means communicates with said first
permitting means so as to permit fluid to flow through said
fitting, said connecting means extends through said second member
and said thread-cutting means cuts internal threads into the
internal surface of the manifold in such a manner that said
thread-cutting means cooperates with the internal threads to
fixedly position said second member in the counterbore of the
manifold and to prevent the inadvertent removal of said first
member from the open end of the manifold; and solvent bonding said
connecting means of said first member to the conduit.
Description
BACKGROUND OF THE INVENTION
To harness solar energy, it is necessary to collect heat in a
system or convert it directly to electricity through silicon solar
cells. Systems for collecting solar energy vary. One of the more
conventional systems involves circulating a fluid, such as water,
through a collector unit. In such a unit, the solar energy
impinging on the collector unit, through a heat exchange process,
is transferred by conduction to the fluid. Obviously, the heated
fluid can then be circulated to put the retained heat to useful
purposes.
Such collector units can be constructed of glass, metal or plastic.
Glass collectors are prohibitively expensive. Due to costs and
other factors, plastic collector units appear to have an edge on
units constructed of metal. With proper construction and
compounding, plastic collector units have the advantage of a much
lower cost coupled with resistance to corrosion, scaling and mild
freezing conditions. These latter factors are extremely important
in a direct circulation system where the pool or tap water passes
through the collector unit, rather than accomplishing a heat
transfer in a secondary heat exchanger device remote from the
collectors.
Plastics which have been found especially suitable for collector
units include the polyolefins, and particularly, the low-cost
polyethylenes and polypropylenes. These latter plastics can be
compounded with stabilizers to reduce ultra-violet degradation and
are serviceable in environments where there is direct sunlight
impingement on their surfaces, even when glazed enclosures are used
to achieve a hot-house effect about such collector units.
Temperatures of the collector units can be over 200.degree. F.
(93.degree. C.) in such systems.
With the proper design parameters, these polyolefins make very
acceptable solar collector units; however, they have a drawback
when collectors fabricated from them are to be joined with the more
conventional plastic piping such as ABS and/or PVC. ABS plastics, a
family of amorphous thermal plastics, are a combination of the
monomers of acrylonitrite, butadiene and styrene which can be
solvent-welded like PVC (polyvinyl chloride) plastics. However,
neither PVC nor ABS piping and/or fittings can be solvent-welded to
the polyolefins. As a result, some mechanical connection must be
effected between a collector unit constructed of a polyolefin and a
conventional ABS or PVC plumbing system.
Because the polyolefins mentioned above are soft, especially at
elevated temperatures found in collector unit applications,
conventional mechanical coupling devices are typically
unacceptable. Fittings connected with screws in the outlet piping
of such a collector unit typically separate due to the deformation
of the polyolefin occurring where the screw loading is
concentrated. If the service pressure of the fluid circulating in
the collector unit is increased to normal household line pressure
(approximately 80 psi), the problem becomes more acute. This cold
flow tendency of plastics under load is greatly increased under the
elevated temperatures experienced in solar collector unit
applications.
As a result, this invention is directed to an improved internal
mechanical connector for solar collector units fabricated from
polyolefins or the like. In addition, using the new mechanical
connector of this invention, the collector unit can be disconnected
from the plumbing without any damage to it, which is not possible
if solvent welding is employed.
SUMMARY OF THE INVENTION
A mechanical coupling for plastic pipes of polyolefins or the like
includes a cylindrical sleeve, the sleeve having a portion thereof
with external self-tapping threads and a circular sealing member
operably associated with the sleeve, with the circular sealing
member having an O-ring groove centrally disposed on its outer
cylindrical surface and an O-ring received in such groove, whereby
the self-tapping threads of the sleeve member can be employed to
cut internal threads into the end of a plastic pipe, enabling the
sleeve to hold the circular sealing member in the end of the pipe
and allowing the O-ring to effect a seal between the internal
surface of the pipe and the sealing member.
The axial length of the cylindrical sealing member and its diameter
should be adequate to stabilize it in the pipe. This prevents
tipping of this member that may interfere with the O-ring line
seal.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention will be better understood by making reference to the
accompanying drawings in conjunction with the written
specification. In respect to the drawings:
FIG. 1 is a perspective of an end portion of a solar collector
illustrating one of the hollow manifolds through which water or
other fluids can be circulated along with an exploded perspective
of an end plug closure fabricated according to this invention;
FIG. 2 is an elevation of the end plug closure shown in FIG. 1;
FIG. 3 is an embodiment of the invention shown in elevation wherein
the plug portion shown in FIGS. 1 and 2 is replaced with a pipe
nipple member; and
FIGS. 4 and 5 are elevations of two alternate embodiments of the
invention employing integral sleeve and sealing member parts for
connecting a plastic collector unit to a piping or plumbing
system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, a broken-away perspective of a solar collector unit 10
is shown. It is composed of a hollow manifold pipe 11 at each end
(only one being shown) with a plastic collector element 12
connected between the two manifold pipes. A distributor structure
13 interconnects the ends of the collector element and each
manifold pipe as shown, and flows liquid to and from the multiple
channels of the collector element.
Each end of each manifold pipe 11 of the collector unit 10 has a
counter bore 11a providing a stepped bore when progressing into the
manifold pipe. (This is best shown in FIG. 1.) The internal
diameter A of the counter bore of the manifold pipe at its distal
ends is larger than the internal diameter B of the central bore of
this pipe. By machining the counter bore in the pipe, a smooth,
regular sealing surface is provided.
Multiple collector units 10 are normally nested together in a
side-by-side arrangement on a roof in a typical system. Floating
couplings are employed between contiguous units and the outmost
units must have their manifold pipes 11 closed off or connected to
the plumbing used with the system. The current invention is related
to making the necessary mechanical connection to the manifold pipe,
whether it is a connection to the plumbing or merely closing off
the end of the manifold pipe.
To close off an end of a manifold pipe 11, a two-piece internal
coupling 20, according to this invention, can be employed. It
includes a hollow cylindrical sleeve 21 and a plastic plug 22.
The hollow sleeve 21 is typically constructed of metal, such as
iron or brass, as can best be seen in FIG. 2. It has a threaded end
21a with external threads 23. The threads are essentially a type of
self-tapping pipe thread, from a smaller diameter progressively to
a larger diameter from the distal end toward the central section of
the sleeve. The counter bore 11a in the end of the manifold pipe
should be 70% to 90% of the diameter of the self-tapping threads on
the sleeve to avoid breakage of the pipe as the sleeve is turned
into the end of this counter bore to cut original internal threads
therein.
Prior to the insertion of the threaded end 21a of the sleeve 21
into the end of the manifold pipe 11, the plug 22 is inserted. This
plug is nothing more than a cylindrical slug with an O-ring 24
centrally disposed thereon, as shown in FIGS. 1 and 2. A matching
O-ring groove formed in the plug is cut to a depth of at least half
the diameter of the O-ring and, of course, both the plug and the
O-ring are sized to give a satisfactory seal in the counter bore
11a.
Once the plug 22, with its assembled O-ring, is inserted into the
open end of the counter bore of the manifold pipe 11, it is
followed by the sleeve 21 which forces it axially into the counter
bore. When the external threads 23 of the sleeve engage the counter
bore, a pipe wrench can be employed to rotate the sleeve until it
has threadedly seated in the end of the manifold pipe.
It can be appreciated that the plug 22 essentially floats in the
counter bore 11a. Thus the hydraulic forces tending to force the
plug out of the end of the counter bore are resisted by threaded
engagement between the sleeve and the manifold pipe when the plug
abuts against the internal end of the sleeve. Because the threaded
engagement provides a substantial circular area of interference
contact between these parts, the hydraulic load is distributed
uniformly and the tendency of the plastic to cold flow will not be
sufficient to allow the sleeve to be pushed out of the end of the
manifold pipe. Of course, the area of the counter bore 11a where
the self-tapping sleeve 21 cuts threads cannot be pre-threaded,
because the O-ring or the plug could be damaged when passing over
such threads. Further, when the unit is fabricated, it is unknown
whether its manifold pipe will need to be closed off or coupled
with a plumbing system, or connected as a central unit in a nest of
such units. Thus pre-threading the counter bore 11a is not
desirable, as it limits the flexibility of the units.
In place of plug 22, it is also possible to use the self-tapping
sleeve 21 with a nipple 30 as is shown in FIG. 3. This nipple has a
construction much like the plug, but includes a tubular extension
31 that is received in the bore of the hollow sleeve 21. This
tubular extension is typically made of ABS or PVC plastic, as is
the head 32 of the nipple. Like the plug, the head includes an
O-ring 33 which is received in a circular groove 34 cut in the
central peripheral surface of the head. A bore 35 extends
completely through the nipple, and once the nipple is secured with
the sleeve 21, a piping system of ABS or PVC can be solvent-welded
to the distal end of the tubular extension to connect the collector
unit into a plumbing system.
In FIG. 4, an integral construction for the internal coupling is
shown. It is similar to the two-part embodiment shown in FIG. 3.
This integral coupling 40 is basically a unitary cylindrical tube
41 having a central bore 42 with an outer cylindrical portion 43
and an inner cylindrical portion 44 connected with a self-tapping
threaded central portion 45. The distal end of the outer
cylindrical portion includes a flared rim 43a that assists in
sealingly connecting hoses and the like. The inner cylindrical
portion has a slightly smaller outer diameter, and its central
section includes an O-ring 46 in a pre-formed groove 47.
Since the threads 48 on the central portion 45 of the integral
coupling 40 are of the same self-tapping construction as the
threads on the sleeve 21, it can be appreciated that this coupling
can be inserted into the end of the manifold pipe 11 until the
threads engage the counter bore and a pipe wrench used on the outer
portion 43 to rotate it until matching threads have been cut in the
counter bore 11a of the collector unit 10. Normally, the integral
unit is constructed of iron or brass.
The integral coupling 50 shown in FIG. 5 is a slight variation of
the one shown in FIG. 4. It also uses a tubular member 51, but can
be constructed of metal or plastic. It is adapted to fit snugly
into the counter bore 11a of the manifold pipe 11. Located
centrally on the tubular member is an O-ring groove 52 in which an
O-ring 53 is received. The coupling is hollow and includes a
tapered end 54 which is equipped with self-tapping threads 55
capable of cutting new threads in a polyolefin pipe structure. In
this embodiment, the threads on the coupling 50 engage the smaller
inner diameter B of the manifold pipe 11. Since the outer diameter
of threads 55 is smaller than the diameter of the counter bore 11a,
the passage of the self-tapping threads across the surfaces of the
counter bore will not scratch or mar this sealing surface.
Again, the end coupling 50 protruding from the manifold pipe 11 can
be grasped with a wrench and the coupling turned to cut threads
into the smaller internal bore of the pipe.
* * * * *